The present invention relates to apparatus and method for rapidly oscillating specimen containers or vessels and, more particularly, to apparatus especially suited for use in recovery of RNA from source material such as a bacteria, a biological tissue, a plant tissue etc and wherein separation of RNA from the cell walls of the source material is effected by the high velocity of impact to which the specimen material is subjected during the oscillating movement of the vessels causing fracturing of the cell walls of the material to release the RNA.
Recovery of RNA is desirable from the perspective of utilization of the recovered RNA for diagnostic, therapeutic and analogous purposes. Chemical separation of the RNA from a source is a commonly used separation practice but has the disadvantage of lengthy processing time.
It also is known to mechanically lyse source material to release genetic material such as RNA or DNA. Generally this involves subjecting the source material to mechanical force and energy that disrupts the cells with violent impact action with consequent release of the RNA. The released RNA then is recovered, e.g., from a liquid phase of the starting material, such procedure being known in the art. One mechanical lysing protocol employs bead mill separation, the source material being confined in a vessel in a liquid phase thereof, there also being minute or small sized beads contained in the vessel. Rapid oscillation of the vessel is used to impart impact energy to the beads and these strike the source material cells repeatedly to open the cells so the RNA can release.
Certain known separation devices and particularly bead mill types are limited as to production capacity, i.e., the number of specimen vessels that can be oscillated at one time. For example BEAD BEATER bead mills manufactured by BioSpec Products of Bartlesville, Okla., for a long time only could be used to oscillate one specimen at a time, although recently a bead mill for use with up to eight specimen vessels at one time has been introduced. These bead mills either single or plural specimen holding, operate to reciprocate the specimen holding vessels horizontally with respect to a horizontal axis defined by a rapidly rotating shaft that drives the oscillating mechanism. Where plural specimen vessels are oscillated together, they have been clustered close about the horizontal axis. A disadvantage of that arrangement is that reproducibilty of oscillating conditions to be the same in each vessel is difficult, if at all possible, to achieve. Where a separation protocol is to be practiced, conditions occurring in each specimen should be replicated identically in each.
Oscillating a cluster of specimen vessels along a horizontal or near horizontal axis and involving use of bead mills of the above description presents serious balance problems in the oscillation producing mechanism creating destructive effects leading to short mechanism service life, the effect of horizontal oscillation on the mechanism bearing unit, for example, being most extreme.
Another shortcoming of known bead mills is lack of capacity to produce oscillations greater than about 2800 oscillations per minute (about 46 Hz). As a result, these bead mills are not capable of disrupting the cells of certain types of RNA source material, and hence resort must be had to chemical lysing.
In dealing with the quest for improving mechanical lysing of RNA, it is seen that apparatus that allows simultaneous separation of plural samples at very high oscillating rate while maintaining optimum balance in the apparatus heretofore was not available, this being attributable in part to understanding that to combine high oscillation rate with high average linear acceleration in the material is difficult.
It is desirable therefore, that apparatus and method be provided which more rapidly effects mechanical separation of RNA from a source thereof and does so without adverse effect on the RNA. In particular it is desirable that such apparatus operate at speeds as high as 133 Hz (8000 oscillations per minute) and be effective to impart average linear acceleration to a source material contained in the presence of small sized beads of up to about 400 g or more thereby to produce relatively complete RNA separation in a time period that can be as low as about 15 to 180 seconds where a specimen vessel of 2 ml volume is used to contain the specimen (50-200 microliters), about a half cc of small sized beads and about one ml of liquid.